Monique J Windley1, Najah Abi-Gerges2, Bernard Fermini3, Jules C Hancox4, Jamie I Vandenberg1, Adam P Hill5. 1. Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, 405 Liverpool Street, Sydney, NSW 2010, Australia; St. Vincent's Clinical School, University of New South Wales, Sydney, NSW 2052, Australia. 2. AnaBios Corp., 3030 Bunker Hill St., San Diego, CA 92109, USA. 3. Coyne Scientific, LLC, 58 Edgewood Ave NE Atlanta, GA 30303, USA. 4. School of Physiology, Pharmacology and Neuroscience, University of Bristol, UK. 5. Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, 405 Liverpool Street, Sydney, NSW 2010, Australia; St. Vincent's Clinical School, University of New South Wales, Sydney, NSW 2052, Australia. Electronic address: a.hill@victorchang.edu.au.
Abstract
INTRODUCTION: The Comprehensive in vitro Proarrhythmic Assay (CiPA) aims to update current cardiac safety testing to better evaluate arrhythmic risk. A central theme of CiPA is the use of in silico approaches to risk prediction incorporating models of drug binding to hERG. To parameterize these models, accurate in vitro measurement of potency and kinetics of block is required. The Ion Channel Working Group was tasked with: i) selecting a protocol that could measure kinetics of block and was easily implementable on automated platforms for future rollout in industry and ii) acquiring a reference dataset using the standardized protocol. METHODS: Data were acquired using a 'step depolarisation' protocol using manual patch-clamp at ambient temperature. RESULTS: Potency, kinetics and trapping characteristics of hERG block for the CiPA training panel of twelve drugs were measured. Timecourse of block and trapping characteristics could be reliably measured if the time constant for onset of block was between ~500ms and ~15s. Seven drugs, however had time courses of block faster than this cut-off. DISCUSSION: Here we describe the implementation of the standardized protocol for measurement of kinetics and potency of hERG block for CiPA. The results highlight the challenges in identifying a single protocol to measure hERG block over a range of kinetics. The dataset from this study is being used by the In Silico Working Group to develop models of drug binding for risk prediction and is freely available as a 'gold standard' ambient temperature dataset to evaluate variability across high throughput platforms.
INTRODUCTION: The Comprehensive in vitro Proarrhythmic Assay (CiPA) aims to update current cardiac safety testing to better evaluate arrhythmic risk. A central theme of CiPA is the use of in silico approaches to risk prediction incorporating models of drug binding to hERG. To parameterize these models, accurate in vitro measurement of potency and kinetics of block is required. The Ion Channel Working Group was tasked with: i) selecting a protocol that could measure kinetics of block and was easily implementable on automated platforms for future rollout in industry and ii) acquiring a reference dataset using the standardized protocol. METHODS: Data were acquired using a 'step depolarisation' protocol using manual patch-clamp at ambient temperature. RESULTS: Potency, kinetics and trapping characteristics of hERG block for the CiPA training panel of twelve drugs were measured. Timecourse of block and trapping characteristics could be reliably measured if the time constant for onset of block was between ~500ms and ~15s. Seven drugs, however had time courses of block faster than this cut-off. DISCUSSION: Here we describe the implementation of the standardized protocol for measurement of kinetics and potency of hERG block for CiPA. The results highlight the challenges in identifying a single protocol to measure hERG block over a range of kinetics. The dataset from this study is being used by the In Silico Working Group to develop models of drug binding for risk prediction and is freely available as a 'gold standard' ambient temperature dataset to evaluate variability across high throughput platforms.
Authors: Nathalie Nguyen; William Nguyen; Brynna Nguyenton; Phachareeya Ratchada; Guy Page; Paul E Miller; Andre Ghetti; Najah Abi-Gerges Journal: Front Physiol Date: 2017-12-19 Impact factor: 4.566
Authors: Kevin R DeMarco; Slava Bekker; Colleen E Clancy; Sergei Y Noskov; Igor Vorobyov Journal: Front Pharmacol Date: 2018-02-01 Impact factor: 5.810
Authors: Oliver J Britton; Najah Abi-Gerges; Guy Page; Andre Ghetti; Paul E Miller; Blanca Rodriguez Journal: Front Physiol Date: 2017-08-18 Impact factor: 4.566
Authors: Jose Vicente; Robbert Zusterzeel; Lars Johannesen; Jay Mason; Philip Sager; Vikram Patel; Murali K Matta; Zhihua Li; Jiang Liu; Christine Garnett; Norman Stockbridge; Issam Zineh; David G Strauss Journal: Clin Pharmacol Ther Date: 2017-11-16 Impact factor: 6.875